Antistatic agents for high-polymeric compounds



United States Patent 3,547,863 ANTISTATIC AGENTS FOR HIGH-POLYMERIC COMPOUNDS Franz Landauer and Hans-Joachim Vetter, Frankfurt am Main, Germany, assignors, by mesne assignments, to Hercules Incorporated, Wilmington, De]. No Drawing. Filed Jan. 23, 1967, Ser. No. 610,822 Claims priority, appliclgtionzgsrmany, Jan. 28, 1966,

US. Cl. 26093.5 5 Claims ABSTRACT OF THE DISCLOSURE Antistatic substances as additives to high-polymeric compounds prepared from oxazolines by reaction with alkylene oxide.

The present invention relates to antistatic agents for high-polymeric compounds.

In the manufacture and work-up of high polymeric compounds which, as is known, are good insulating materials, and also when using the articles made thereof, electrostatic ,charging occurs which frequently causes disturbances. This electrostatic charging does not only result in the articles adhering to each other or repelling each other, but also in their attracting dustand dirt particles. There have already been recommended different ionic or non-ionic antistatic agents, such as quaternary ammonium salts, as well as amines and amides as such or those which have been alkylene-oxylated, furthermore amino alcohols and the esters thereof, conversion products of fatty acids or high molecular weight alcohols with alkylene oxide, siloxanes, organyl-sulfonates and derivatives of phosphoric acid, which are added to the highpolyineric compound prior to the work-up or which are applied to the shaped articles in the form of an aqueous or organic solution. However, the anti-static eflicacy or the other properties are generally not satisfactory, such as poor compatibility with the high-polymer as such or with other auxiliary agents, as well as self-odor, decomposition, i.e. discoloration on being worked up, liability of the antistatic layer of being easily washed off with water, a low light resistance and exudation. In many cases it is also necessary to subject the shaped articles to a flame treatment or to a high-frequency discharge in order to render the antistatic effect effective. In some cases this effect develops only after a prolonged period, for example after several weeks, so that the material may become soiled or may attract dust already previously.

It is, above all, a disadvantage for the applicability of polyethylene glycol or ethoxylated fatty acids, alcohols or amines as antistatic agents that they have a relatively high tendency of exuding from high-polymeric organic compounds, which results in smeared surfaces which can be printed with difiiculty only. With the use of ethoxylated alcohols or amines, moreover, a disagreeable odor becomes noticeable, said alcohols or amines bringing about a discoloration, for example, in polyethylene and polypropylene. In spite of a satisfactory antistatic efficacy, these properties very much limit the range of application of the antistatic agents.

Now we have found that high-polymeric compounds can advantageously be rendered resistant to electrostatic charge by using conversion products of oxazolines of the formula ice in which R represents an alkyl-, arylor cycloalkyl radical containing 3 to 20 carbon atoms, A being CH O-CH, or S-CH R represents an alkyl radical con taining 1 to 4 carbon atoms or the radical y being a whole number from 1 to 3, and R represents the radical (CH -O-H, with 3 to moles alkylene oxide, preferably ethylene oxide and/or propoylene oxide, especially 5 to 60 moles ethylene oxide per mole of oxazoline, in an amount within the range of from 0.05 to 4 percent by weight, preferably 0.5 to 1.5 percent by weight, calculated on the high-polymeric compound.

As substituted oxazolines there may be used, for example, the addition products of alkylene oxides, especially of ethylene oxide and/or propylene oxide, and

2-hexyl-4-methyl-4-hydroxymethyl-oxazoline, 2-a-ethylpentyl-4-ethyl-4-hydroxymethyl-oxazoline, Z-undecyl-4,4-bis-hydroxymethyl-oxazoline, 2-heptadecyl-4-hydroxymethyl-oxazoline, 2-heptoxy-methylene-4-ethyl-4-hydroxymethyl-oxazoline, 2-phenyl-4-ethyl-4-hydroxymethyl-oxazoline.

The oxazolines can be prepared according to known processes, for example according to US. Pat. 2,504,951, from aromatic carboxylic acids or from saturated or unsaturated aliphatic or cycloaliphatic monocarboxylic acids, which may be linear or branched, or from mixtures of these carboxylic acids such, for example, as stearic acid or coconut oil acid, by reaction with alkylol amines (1,2), carrying at least two hydroxyl groups, such, for example, as 2-amino-2-ethyl-propanediol-(1,3), 2-amino- 2-methyl-propanediol-(1,3) or trishydroxymethyl-aminomethane with the splitting off of two moles water at an elevated temperature and, if desired, under reduced pressure. The hydroxyl groups of the substituted oxazolines obtained in this manner can then be converted according to the usual processes, for example according to the process known from German Auselgeschrift 1,027,672, with epoxides such as, for example, ethylene oxide or propylene oxide or mixtures of these epoxides.

Depending on the ramification and the number of the carbon atoms of the hydrocarbon radical R at the oxazolines nucleus in combination with the amount of ethylene oxide and/or propylene oxide, there are obtained products having a more or less pronounced hydrophilic or hydrophobic character, for which reason the substances may not only be incorporated as water-insoluble antistatic agents to the high polymeric compound but may also be used in the form of an aqueous or organic solution, for example in chlorohydrocarbons, such as carbon tetrachloride, esters, such as ethyl acetate, ketones, such as acetone, or aromatic hydrocarbons, such as benzene, for the treatment of finished shaped articles.

The antistatic agents used according to the present invention improve the blocking resistance of the plastic materials during the work-up and diminish blocking, that is to say, sticking of the finished articles, but above all, they diminish electrostatic charging. Even when being used in small amounts, the antistatic agents described above exhibit a high permanent elficacy; they withstand the high temperatures applied during the work-up and do not produce discolorations. Moreover, they are well compatible with the plastic material. Exudation does not occur if the concentration is not too high.

All high-polymeric organic compounds can be rendered resistant to electrostatic charging in accordance with the process of the present invention, polyolefins and polyesters being especially suitable. As polyolefins there may be used, for example, homopolymers of ethylene, propylene, 4-methyl-pentene-1, styrene and isoprene, furthermore copolymers of ethylene and propylene, 4-

3 methylpentene-l and l-olefines, furthermore copolymers of styrene and acrylonitrile, methacrylonitrile or diolefins, such as butadiene-1,3. By polyesters there are understood, for example, polymeric esters of terephthalic acid and glycols having 2 to 10 carbon atoms.

4 (indicated in the table by V). V means measurement directly after the preparation of the test body, V means measurement after the test body has been wiped off with a wet cloth and allowed to dry for a period of 5 hours.

To examine the antistatic efiicacy there was, further- The antistatic agent can be incorporated to the high- 5 more, carried out the following carbon black test: The polymeric compound by admixture in the dry state, by test sheet was moved to and fro under slight pressure on rolling or granulation, or in a Banbury mixer (R). The a standard cloth (wool) having the dimensions x antistatic additive may be applied in the form of a cm. and held above a layer of carbon black at a distance solution in a solvent that swells the high-polymeric com- 10 of 0.5 cm.

Pound P or be i is i means attraction of carbon black suspenslon or a dlsperslon the me mm emg means no attraction of carbon black evaporated after the treatment of the powder, granular product or finished Shaped m All measuiements were carried out at a temperature Other conventional additives, such as stabilizers, fillers, 15 ofzo and g g i molsture of dyestuffs, lubricants, plasticizers or pigments are not pelcan (atmosp cnc Stan F" F moms) 1 to th ntistatic eficacy In many cases it is In the examples the antistatic agents were used in a Prelu ma e a 1 v 1 the antistatic agents 1 percent concentration. The processing temperatures 0 advantaeeou? to 5 y Se era t th r or to (molding press) were 160 C. for polyethylene, 200 C. used accordmg to t e present inven ionh oge eh th 90 for polypropylene, 0 c. for polystyrene and 0 pply l Oxalkylated oxazohnes toga er 0 er for poly(ethylene-terephthalate). The values combined antlstatlc in the table following hereunder show the electrostatic The antlstatlc mass s Obtalned can be f f P by behaviour of the high-polymeric compounds rendered rethe Conv nti methods, for example y lnlectlon-mold sistant to electrostatic charge by means of the antistatic ing, extrusion-molding or deep drawmg. agents applied according to the present invention.

The following examples serve to illustrate the lnven- 0 After storing the test bodies at elevated temperatures, tion, but they are not intended to limit it thereto, the and then cooling them to -40 C., exudation was not pgrcentages being by Weight; observed. Even when heating the masses applied accord- E l 1 t 24 ing to the present invention intensively in the cylinder Xamp es 0 30 of an injection molding machine for a prolonged period, The antistatic agents listed in the table were dissolved discolorations did not occur.

TABLE Surface Surface Carbon Example voltage voltage black No. Polymer Additive V1 V21 test No additive 2790 29l0 2-heptadecyl-4-ethyl-4-hydroxymethyloxazoline.40 EO '1l0 +100 2-a-ethylpentyl-iethyll-hydroxymethyloxa- 37 370 z01ine.40 EO. 2-naphtenyl-l-etl1yl-4-hydroxymethyloxazoline.30 EO +100 290 2-undecyl-4-ethyl-4-hydroxymethyloxazoline.5 EON-.. 18 405 2-heptadecyl-4-ethyl-4-hydroxymethyloxaz0line.3 350 P1'O.20 E05 No additive -2,700 -2,s05 Z-heptadeeyl-4-ethyl-4-hydroxymethyloxazolineAO EO -400 2J1eptadecyl-l ethyli-hydroxymethyloxazoline.5 EO +100 450 2-undecyl-4-ethyl-4-hydroxymethyloxazoline.5 EON 18 380 2-undecyl-4,4-bis-hydroxymethyloxazoline.30 EO 200 -500 2-naphtenyl-4-ethyl-4-hydroxyrnethyloxazoline.30 E l60 43O Z-hepgpymethylene-4-ethyl-4-hydroxymethyloxazoline- 370 .20 2-dodecyl-mercaptomethylene-4metliyl-lhydroxy- 145 490 methyloxazoline.10 E0. No additive 3, 2-undeeyl-4-ethyl-4-hydroxymethyloxazoline.30 E0 +10 60 2-undecyl-4ethylt-hydroxymethyloxazoline.100 EO 310 -222 2a-ethylpentyl-4-ethyl-4-hydr0xymethyloxa- +260 +148 zolineAO E0. 2-heptadecyl-4ethyl-4-hydroxymethyloxazoline.5 EO 185 225 No additive 2, 200 2'a-ethylpentyll-ethyl-l-hydroxymethyloxa +60 70 z0line.30 EO. 2-11eptadecy1-4-ethyl-4-hydroxymethyloxazoline.5EO -55 2-naphtenyl-A-ethyl-4-hydroxymethyloxazoline.40 E0... 90 -148 2-0ctyl-l-ethy1-4-hydroxymethyloxazoline.40 E0 +150 95 3 E0 ethylene oxide, PrO propylene oxide.

and mixed with the pulverulent plastic material in an impelled. The solvent was quantitatively evaporated in vacuo at elevated temperatures. From the mixtures so obtained 1 mm. thick pressed sheets were made between chrome plated brass plates.

To examine the antistatic efficacy, tribe-electric voltages produced on test sheets were compared with each other. To this effect, electrostatic charges were produced on a sample (7 x 7 cm. x 1 mm.) oscillating in a horizontal direction, by means of a cylinder covered with a woolen cloth and rotating at a constant speed. The electrostatic maximum charge produced by repeated friction was determined by an electro-statometer Which was fixed at a distance of 6 cm. from the test sheet 4 PE=linear (low-pressure) polyethylene. 5 PS=polystyrene. PETP=p0lyethylene terephthalate.

electrostatic charge conselected from the group of a-rnono-olefins, an polystyrene, a styrenewherein R stands for alkyl, aryl or cycloalkyl containing 3 to 20 carbon atoms, A stands for CH -CH or S-CH R stands for alkyl having 1 to 4- carbon atoms or -(CH )y-O-H wherein y is a whole number from 1 to 3, and R stands for-(CH )yO-H wherein y is a whole number from 1 to 3, with 3 to 100 moles of ethylene oxide, propylene oxide or mixtures thereof per mole of oxazoline, said addition of said oxide taking place by reaction of the oxide with a free hydroxyl group on the oxazoline.

2. The composition according to claim 1 wherein the antistatic agent is present in an amount between 0.5 to 1.5 percent.

3. The composition according to claim 1 wherein the oxazoline is 2-hexyl-4-methyl-4-hydroxymethyl oxazoline, 2oz ethylpentyl-4ethyl-4-hydroxymethyl oxazoline, 2-undecy1-4,4-bis-hydroxymethyl-oxazoline, 2-heptadecy1- 4-hydroxymethyl-oxazoline, Z-heptoxy-methylene-4-ethy1- 4-hydroxymethyl-oxazoline or 2-phenyl-4 ethyl 4 hydroxymethyl-oxazoline.

6 4. The composition according to claim 1 wherein the polymer is polyethylene or polypropylene.

5. The composition according to claim 1 wherein the polymer is polystyrene.

References Cited UNITED STATES PATENTS 2,636,038 4/1953 Brandner 260-307.6

3,110,732 11/1963 Speranza et a1. 260-307.6 2,965,678 12/ 1.960 Sundberg et a1. 260-615 3,190,763 6/1965 Schleede et a1. 106-186 FOREIGN PATENTS 1,006,115 4/1957 Germany 260-Anti Static 15 1,323,473 2/1963 France 260-307.6

JAMES A. SEIDLECK, Primary Examiner US. Cl. X.R. 

